1. Field of the Invention
The invention generally relates to apparatus for purifying and sterilizing ambient air, and more specifically to an aspiration unit for conditioning ambient air during rail car unloading of perishable food products.
2. Description of the Prior Art
Perishable food products are often shipped in rail cars to bulk break stations. At these stations, the rail cars are unloaded into stainless steel tank trucks, which in turn deliver the food products to the ultimate customers. These break stations act as distribution points for varying perishable food products, such as corn syrup products. When the rail cars arrive at a break station for off-loading into trucks, the rail car must be properly vented. Trucks are connected via hoses to the bottom of the rail car and a product in liquid form, such as syrup, is pumped from the rail car to the truck. When this occurs, air must be supplied to the interior of the rail car to replace the syrup removed from the car. If the vent structures or access ports at the top of the rail car is merely opened to allow ambient air to flow in to avoid a vacuum in the head space above the liquid product being unloaded, various pollutants, including dust, bees, insects, air born yeast or mold spores, can enter into the car and contaminate the syrup. Furthermore, several days could pass before the rail car is again unloaded into a different truck at the same location. During this intervening time, cold air introduced into the rail car in the presence of warm syrup causes condensation to take place. The condensation on the metal surfaces inside the car causes dripping and provides areas for high potential of microbiological growths which leads to mold and bacteria formation.
In U.S. Pat. No. 4,896,590 to Groos, a railroad hopper car vent is disclosed which permits filtered air to be drawn into the rail car to take the place of the material that is being discharged. However, Groos merely teaches the use of a railroad hopper car vent that relies on a filter for removing contaminants from the ambient air prior to being admitted into the rail car. See also U.S. Pat. No. 4,315,579 to Martin, Jr. which discloses a venting and filtering mechanism for a milk tank vent and which utilizes a sheet of filter material secured to the closure member or manhole cover to prevent entry of contaminants into the interior of the tank.
U.S. Pat. No. 3,326,111 to Stevens also dislcoses a removable filter on a vent structure for a covered hopper railway car. The circulation of heated air through a railway car is disclosed, the heated air being fed into the bottom of the hoppers and exhausted at one end of the car. A shielding stream of electrically heated air is admitted at the other end of the car near the roof which flows along the roof to prevent moisture laden circulated air from striking the cold roof directly, and thus preventing condensation. The railway car described, however, is primarily designed to remove excessive moisture released by fruits and vegetables. Excessive moisture in the railway car, resulting from the respiration of such fruits and vegetables, can damage the product being transported.
It is also known to provide portable apparatus for heating or cooling ambient air outside of a car for providing the heated or cooled air to the inside of the car. See, for example, U.S. Pat. No. 1,811,529 to Barstow et al. which discloses a portable apparatus for conditioning perishable products in a railway car. The apparatus provides a pre-ripening gas and provides for maintenance of desired conditions of temperature and humidity. U.S. Pat. No. 1,921,178 to Wood discloses a temperature control apparatus installed outside a railway car. Here, the apparatus has a fan and cooling coils across which air is blown before entering the car. The objective in Wood is to maintain the cargo being transported within predetermined temperature ranges, below a predetermined temperature but not so low that the goods may be frozen or otherwise damaged. Provision is, therefore, made for cooling or heating the air directed into the refrigerator car to compensate for the outside or ambient air temperature.
While the earlier approaches, therefore, have recognized that air drawn into rail cars during unloading must be regulated in temperature and cleaned of contaminants, such units have not been fully effective in conditioning the ambient air by sterilizing, filtering and heating it prior to being directed into the head space of the railway car above the perishable food product.
While stationary and portable air purifiers have been known, such as those described in U.S. Pat. No. 3,757,479 to Sievers and U.S. Pat. No. 4,786,812 to Humphreys, these have been proposed for use in offices, hospitals, food processing centers and the like. However, in germicidal ultraviolet lamp units have not been combined with mechanical filtering and temperature control to optimize the conditioning of ambient air received within a rail car unloading of perishable food products.
Accordingly, it is an object of the present invention to provide an aspiration unit for conditioning air during rail car unloading of perishable food products which does not have the disadvantages encountered in the prior art units.
It is another object of the invention to provide an aspiration unit of the type under discussion which is simple in construction and economical to manufacture.
It is still another object of the present invention to provide an aspiration unit for use with rail cars which is both effective to remove large contaminants, such as insects, dust, air born yeast and mold spores, as well as bacterial contaminants.
It is yet another object of the present invention to provide an aspiration unit of the type under discussion which provides mechanical filtering, temperature control as well as ultraviolet exposure to ambient air before it is permitted to enter into the head space inside a rail car during removal of the contents thereof.
It is a further object of the present invention to provide an aspiration unit as suggested in the previous objects which can be easily positioned in place within a vent structure or access port of a rail car prior to the unloading of perishable food products, and easily removable after unloading has terminated. It is still a further object of the present invention to provide an aspiration unit as in the foregoing objects which can be utilized during extreme ambient temperature conditions, without materially affecting the effectiveness of the unit.
In order to achieve the above objects, as well as others which will become apparent hereafter, a tank car unloading aspiration unit in accordance with the present invention for conditioning air received within the head space inside a tank car during removal of the contents of the tank car and replacement of the removed contents with the air comprises an air transfer portion configurated and dimensioned to be received within an access port in the roof of a rail tank car. Inlet conduit means is provided for directing conditioned air into the head space and outlet conduit means for removing air from the head space. Cover means is provided for covering the aspiration unit, and intake means for admitting ambient air into the unit. Conditioning means between said cover means and said air transfer portion condition the ambient air by heating the air to a temperature within a predetermined range and exposing the air to electromagnetic radiation. Air movement means is provided for drawing ambient air through said intake means and expelling the conditioned air through said inlet conduit means after passage of the ambient air through said conditioning means.